The present invention relates to a tape printing device that is configured such that a tape-form thermal recording medium (hereinafter, simply referred to as a tape) is pressed against a thermal head, letter/characters are printed on the tape, and a portion of the tape on which the letters/characters are printed is discharged to outside.
Conventionally, various types of tape printing devices are proposed. An example of the conventional tape printing devices is configured such that the tape is fed by a platen mechanism, which is movable between an operating position and a standby position in association with an attachment/detachment (i.e., attaching/detaching or opening/closing) of a back cover for covering a cassette holding section. Then, the tape is pressed against a thermal head by the platen. The thermal head applies heat to the tape in accordance with print data to form letters/characters on the tape. Then, the printed portion of the tape is discharged outside.
Examples of the tape printing device are further described. In Japanese Patent Provisional Publication No. HEI 08-25753, a tape printing device provided with a tape feeding mechanism, a thermal head for forming letters/characters on the tape, a platen that is retractably urged toward the thermal head is disclosed. The tape feeding mechanism, the thermal head and the platen are provided within a frame of a tape cassette holding section that accommodates a tape cassette. Further, in this publication, the platen is supported by a platen holder that is swingably supported by a holder shaft. The holder shaft stands on a base plate, and a head supporting member mounting a thermal head is disposed on the base plate. The position of the thermal head with respect to the platen is previously adjusted, and the base plate is secured on the frame by means of screws.
For another example, U.S. Pat. No. 5,839,840 discloses a tape printer having a platen mechanism which moves between an operable position and a retracted position in association with attachment/detachment of a back cover that covers a tape cassette holding section. In this example, when the back cover is attached to the tape printer, an engaging protrusion standing on an inner surface of the back cover is interposed between the movable platen and a fixed member, thereby the platen holder is swung toward the tape cassette until a portion of the tape is pressed against the thermal head by the platen.
In the above-mentioned prior art in which the holder shaft stands on the base plate and the head supporting member provided with the thermal head is mounted on the base plate with the position thereof previously adjusted, the head supporting member is typically made as a metal member, which is produced, for example, by aluminum die-casting. Thus, it is necessary to secure the head supporting member on the base plate made of metal by means of screws, which raises a problem of increasing working processes and a manufacturing cost.
In the configuration in which the engaging protrusion formed on the inner surface of the back cover is interposed between the platen holder and the fixing member to swing the platen holder toward the tape cassette to urge the tape of the tape cassette against the thermal head, the supporting plate provided in the tape mounting portion for supporting the thermal head is typically made of resin. Therefore, the supporting plate can be formed by a single resin molding process, and hence the manufacturing cost can be reduced. However, when it is used at high temperatures for a long time, a problem raises that creep deformation of the supporting plate occurs in a direction pressed by the platen holder. When the deformation occurs, the printing quality is deteriorated.